The present invention relates to a prober that connects an electrode of a die to a probe to be connected to a terminal of a tester in order to conduct electrical inspection of a plurality of devices (dies) formed on a semiconductor wafer and a probe contact method for touching a probe to an electrode, and more particularly, to a prober that inspects a wafer while maintaining it at a high or low temperature and a probe contact method therefor.
In a semiconductor manufacturing process, a plurality of devices (dies) are formed by subjecting a thin disk-shaped semiconductor wafer to various processes. After the electrical characteristic of each device is inspected and the devices are separated using a dicer, they are fixed on a lead frame, etc., and then assembled. The above-mentioned inspection of the electrical characteristics are conducted by a wafer test system consisting of a prober and a tester. This inspection is referred to as a probing test. The prober holds a wafer on a stage and touches a probe to the electrode of each device. The tester supplies power and various test signals from a terminal connected to the probe and confirms whether the operation is normal by analyzing the signal output to the electrode of the device using the tester.
The semiconductor device is used for many purposes and some devices are used in a low or high temperature environment, and therefore, a prober is required to be capable of being subjected to inspection in such an environment. In order to cope with this, for example, a wafer temperature adjustment mechanism, such as a heater mechanism, chiller mechanism, etc., which changes the temperature of the surface of a wafer chuck, is provided under the wafer mount surface of a wafer chuck that holds a wafer in a prober and the wafer held on the wafer chuck is heated or cooled down.
FIG. 1 is a diagram showing a general configuration of a wafer test system comprising a prober having a wafer temperature adjustment mechanism. As shown schematically, a prober 10 has a base 11, a movement base 12 provided thereon, a Y axis movement base 13, an X axis movement base 14, a Z axis movement section 15, a Z axis movement base 16, a θ rotation section 17, a wafer chuck 18, an alignment microscope 19, supports 20 and 21, a head stage 22, a card holder 23 provided on the head stage 22, and a probe card 24 to be attached to the card holder 24. The probe card 24 is provided with a probe 25. The movement base 12, the Y axis movement base 13, the X axis movement base 14, the Z axis movement section 15, the Z axis movement base 16, and the θ rotation section 17 constitute a movement/rotation mechanism that moves and rotates the wafer chuck 18 in the directions of the three axes and around the Z axis. A movement control section 43 controls the movement/rotation mechanism. Since the movement/rotation mechanism is widely known, an explanation is omitted here. The probe card 24 has the probe 25 arranged in accordance with the arrangement of the electrodes of a device to be inspected and is exchanged in accordance with a device to be inspected. Although the needle alignment camera 19 that detects the position of the probe, a cleaning mechanism that cleans a probe, etc., are provided, they are omitted here.
A tester 30 has a test head 31 and a contact ring 32 provided at the test head 31. The probe card 24 is provided with terminals to be connected to the respective probes and the contact ring 32 has spring probes arranged so that they come into contact with the terminals. The test head 31 is held with respect to the prober 10 by a support mechanism (not shown). The prober 10 makes a measurement in connection with the tester 30 in a wafer test, however, its power supply system and mechanical sections are independent from the tester main body and the test head.
When conducting inspection, the tip position of the probe 25 is detected by the needle alignment camera (not shown). Next, in a state in which a wafer W to be inspected is held on the wafer chuck 18, the Z axis movement base 16 is moved so that the wafer W is situated under the alignment microscope 19 and the position of the electrode of the device on the wafer W is detected.
FIG. 2 is a diagram showing an array example of devices 1 formed on the wafer W, in which a great number of devices 1 are formed. As shown at the lower portion of FIG. 2, each device 1 has an electrode 2 for supplying electric power from the outside and inputting/outputting signals from/to the outside. In the prober, the electrode 2 of each device 1 comes into contact with the probe 25.
When the position of the electrode of the device is detected, it is not necessary to detect the positions of all of the devices 1, but only the positions of some electrodes. In addition, it is not necessary to detect the electrodes of all of the devices on the wafer W, but is only necessary to detect the positions of the electrodes of some devices. The above-described detection operation of the position of electrode on the wafer is referred to as a wafer alignment operation.
It is assumed that such a relationship between the position detected by the needle alignment camera and the position detected by the alignment microscope 19 is acquired in advance by, for example, touching the probe 25, the tip position of which has been detected by the needle alignment camera, to the surface of the wafer to detect the probe contact trace on the wafer using the alignment microscope 19.
After detecting the position of the probe 25 and the position of electrode of the wafer W, the wafer chuck 18 is rotated by the θ rotation section 17 so that the direction of the array of device electrodes coincides with the direction of the array of the probe 25. Then, after a movement is made so that the electrode of the device to be inspected of the wafer W is situated under the probe 25, the wafer chuck 18 is lifted so that the electrode comes into contact with the probe 25. These movement operations are controlled by the movement control section 43. Then, electric power and test signals are supplied to the electrode from the test head 31 via the contact ring 32 and whether the operation is normal is confirmed by detecting the signal output to the electrode.
The general configuration of the wafer test system is described as above. The prober, in which the wafer chuck is heated or cooled down and capable of conducting inspection while maintaining the held wafer W at a high temperature or low temperature, is provided with a heater 26 and a chuck cooling liquid path 27 within the wafer chuck. A cooling liquid flows through the chuck cooling liquid path 27 from a cooling liquid source 28 via a supply path 29A and cools down the surface of the wafer chuck 18 that holds the wafer W. The cooling liquid having passed through the chuck cooling liquid path 27 is recovered to the cooling liquid source 28 via a recovery path 29B. Here, the portion constituted by the chuck cooling liquid path 27, the cooling liquid source 28, the supply path 29A, and the recovery path 29B is referred to as a chiller system. In addition, the heater 26 generates heat and heats the surface of the wafer chuck 18 that holds the wafer W. Further, a temperature sensor 41 is provided in the vicinity of the surface of the wafer chuck 18 and a control section 42 of the cooling liquid source 28 controls the temperature of the cooling liquid supplied from the cooling liquid source 28 in accordance with the surface temperature of the wafer chuck 18 detected by the temperature sensor 41.
Within the wafer chuck 18, a vacuum path for vacuum adsorption of the waver W, etc., is further provided, and there are various modification examples of the arrangement of the heater 26, the chuck cooling liquid path 27, and the vacuum path within the wafer chuck 18.
When conducting a probing test after the temperature of a wafer is adjusted to a predetermined temperature, the heater 26 or the chiller system is operated so that the wafer chuck 18 reaches the predetermined temperature and then the wafer is held thereon, and in a state in which the wafer W has reached the test temperature, the probing test is started. The wafer chuck 18 is made of a metal, such as aluminum, copper, etc., or a ceramic excellent in thermal conductivity.
The alignment method in a prober is described in, for example, Japanese Unexamined Patent Publication (Kokai) No. H5-343485, Japanese Unexamined Patent Publication (Kokai) No. H11-26520, etc., and the temperature adjustment mechanism of a wafer chuck is described in, for example, Japanese Unexamined Patent Publication (Kokai) No. 2001-210683 etc.